Scale Dependence of Effective Hydraulic Conductivity Distributions in 3D Heterogeneous Media: A Numerical Study

Upscaling procedures and determination of effective properties are of major importance for the description of flow in heterogeneous porous media. In this context we study the statistical properties of effective hydraulic conductivity (Keff) distributions and their dependence on the coarsening scale. First we focus on lognormal stationary isotropic media. Our results suggest that Keff is lognormally distributed independently on the coarsening scale. The scale dependence of the mean and variance of Keff are in agreement with recent analytical derivations obtained using coarse graining filtering techniques. In the second part we focus on binary media, analysing the dependence of Keff distributions on the coarsening scale and also on the high-K facies volume fraction p. When p is near the percolation threshold pc, the decrease of the normalized variance with the coarsening scale is remarkably (102 times) slower compared to the situation in which p far from pc, but also compared to the cases of lognormal media studied before. This result permits to assess the degree of difficulty that systems with p near pc pose for upscaling procedures. Also we point out in terms of Keff statistics the relative influence of the coarsening scale and of the high-K facies connectivity.Fil: Boschan, Alejandro. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Nœtinger, B.. No especifíca

Granular flow through an aperture: Influence of obstacles near the outlet

We study how the presence of obstacles in a confined system of monodisperse disks affects their discharge through an aperture. The disks are driven by a horizontal conveyor belt that moves at constant velocity. The mean packing fraction at the outlet decreases as the distance between the obstacles and the aperture decreases. The obstacles organize the dynamics of the stagnant zones in two characteristic behaviors that differ mainly in the magnitude of the fluctuations of the fraction of stagnant disks in the system. It is shown that the effective aperture is reduced by the presence of obstacles.Fil: Areán, M. G.. Universidad de Buenos Aires. Facultad de Ingeniería. Departamento de Física. Grupo de Medios Porosos; ArgentinaFil: Boschan, Alejandro. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad de Buenos Aires; ArgentinaFil: Cachile, Mario Andres. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad de Buenos Aires. Facultad de Ingeniería. Departamento de Física. Grupo de Medios Porosos; ArgentinaFil: Aguirre, Maria Alejandra. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad de Buenos Aires. Facultad de Ingeniería. Departamento de Física. Grupo de Medios Porosos; Argentin

Characterization of fracture aperture field heterogeneity by electrical resistance measurement

We use electrical resistance measurements to characterize the aperture field in a rough fracture. This is done by performing displacement xperiments using two miscible fluids of different electrical resistivity and monitoring the time variation of the overall fracture resistance. Two fractures have been used: their complementary rough walls are identical but have different relative shear displacements which create “channel” or “barrier” structures in the aperture field, respectively parallel or perpendicular to the mean flow velocity →U. In the “channel” geometry, the resistance displays an initial linear variation followed by a tail part which reflects the velocity contrast between slow and fast flow channels. In the “barrier” geometry, a change in the slope between two linear zones suggests the existence of domains of different characteristic aperture along the fracture. These variations are well reproduced analytically and numerically using simple flow models. For each geometry, we present then a data inversion procedure that allows one to extract the key features of the heterogeneity from the resistance measurement.Fil: Boschan, Alejandro. Universidad de Buenos Aires. Facultad de Ingeniería. Departamento de Física. Grupo de Medios Porosos; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Ippolito, Irene Paula. Universidad de Buenos Aires. Facultad de Ingeniería. Departamento de Física. Grupo de Medios Porosos; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Chertcoff, Ricardo Héctor. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad de Buenos Aires. Facultad de Ingeniería. Departamento de Física. Grupo de Medios Porosos; ArgentinaFil: Hulin, J. P.. Universite de Paris Xi. Laboratoire Automatiques et Systeme Thermiques; FranciaFil: Auradou, H.. Universite de Paris Xi. Laboratoire Automatiques et Systeme Thermiques; Franci

Design and analysis of different models of microfluidic devices evaluated in enhanced oil recovery (EOR) assays

Microfluidic devices are a new platform for Enhanced Oil Recovery (EOR) assays. A successful oil recoveryin a reservoir can be different in another, hence the importance of a methodology for assessment prior toinjection. In the current study, micro and nanotechnology techniques were applied to develop EOR assays.The EOR chips simulated the phenomena occurred in micro-nano scale reservoirs. In general, the first step ofthe experiments corresponded to fill the microchannels with oil, then was injected water at constant flow rateuntil oil recovery ceases and finally was injected polymer or CDG. The recovery behaviors of the fluids werestudied by digital image analysis. Results allowed obtaining oil recovery for each evaluated fluid. Theoptimum configuration of the microchannels showed 80% of oil residual saturation after water injection.Keywords: EOR, poral volume, microgels and polymers, microfuidic devices.Fil: Rosero Yánez, Gustavo Ivan. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Tecnológica Nacional. Facultad Regional Haedo. Grupo de Ingeniería de Recubrimientos Especiales y Nanotecnología; ArgentinaFil: Peñaherrera Pazmiño, Ana Belén. Universidad Tecnológica Nacional. Facultad Regional Haedo. Grupo de Ingeniería de Recubrimientos Especiales y Nanotecnología; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Olmos Carreno, Carol Maritza. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Tecnológica Nacional. Facultad Regional Haedo. Grupo de Ingeniería de Recubrimientos Especiales y Nanotecnología; ArgentinaFil: Boschan, Alejandro. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad de Buenos Aires. Facultad de Ingeniería; ArgentinaFil: Granell, Pablo Nicolás. Instituto Nacional de Tecnología Industrial; ArgentinaFil: Golmar, Federico. Instituto Nacional de Tecnología Industrial; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Lasorsa, Carlos Alberto. Universidad Tecnológica Nacional. Facultad Regional Haedo. Grupo de Ingeniería de Recubrimientos Especiales y Nanotecnología; ArgentinaFil: Lerner, Betiana. Universidad Tecnológica Nacional. Facultad Regional Haedo. Grupo de Ingeniería de Recubrimientos Especiales y Nanotecnología; Argentina. Universidad de Buenos Aires. Facultad de Ingeniería; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Perez, Maximiliano Sebastian. Universidad Tecnológica Nacional. Facultad Regional Haedo. Grupo de Ingeniería de Recubrimientos Especiales y Nanotecnología; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad de Buenos Aires. Facultad de Ingeniería; Argentin

Etude du transport et de la dispersion dans les milieux fracturés

The dispersion of dye in Newtonian and shear-thinning fluids has been studied optically in transparent rough model fractures. The evolution of the displacement front is investigated as a function of time and mean velocity $U$. For a wall roughness given by a random distribution of single-sized obstacles on a flat plane, the front spreading is diffusive ($\Delta x \propto t^{0.5}$) and characterized by a dispersivity $l_d$. At low velocities, $l_d \simeq$ cst.: dispersion is driven by spatial velocity fluctuations which are increased for shear-thinning fluids; at high velocities, Taylor dispersion is dominant and $l_d$ increases with $U$ but slower for shear thinning fluids. For a fracture with complementary self-affine rough walls with a relative lateral displacement perpendicular to $U$, macroscopic channels parallel to $U$ appear and extend all along the length of the model: the global front width increases linearly with time, more rapidly for the shear-thinning fluids (advective spreading). In contrast, the local front spreading remains diffusive and governed by Taylor dispersion.La dispersion de colorant dans des écoulements newtoniens ou rhéofluidifiants a été étudiée optiquement dans deux fractures modèles rugueuses et transparentes. L'évolution du front de déplacement est analysé en fonction du temps et de la vitesse moyenne $U$ . Pour des rugosités de parois monodisperses et distribuées aléatoirement, l'étalement du front est diffusif ($\Delta x \propto t^{0.5}$) et caractérisé par une dispersivité $l_d$. Aux faibles vitesses, $l_d \simeq$ cst: la dispersion est dominée par les fluctuations spatiales de la vitesse et est amplifiée pour les fluides rhéofluidifiants ; aux vitesses élevées, $l_d$ augmente avec $U$ à cause de la dispersion de Taylor mais plus faiblement pour les fluides rhéofluidifiants. Pour une fracture avec deux parois autoaffines complémentaires décalées perpendiculairement à $U$, des chenaux macroscopiques s'étendent sur toute la longueur de la fracture suivant $U$ : l'épaisseur globale du front augmente alors linéairement avec le temps et plus fortement dans le cas rhéofluidifiant (étalement advectif). La croissance de l'épaisseur locale du front est par contre diffusive et due à la dispersion de Taylor

Etude du transport et de la dispersion dans les milieux fracturés

La dispersion de colorant dans des écoulements newtoniens ou rhéofluidifiants a été étudiée optiquement dans deux fractures rugueuses et transparentes. Le front de déplacement est étudiée en fonction du temps t et de la vitesse moyenne U. Pour des rugosités de parois monodisperses et distribuées aléatoirement, l étalement est diffusif et caractérisé par une dispersivité ld. Aux faibles U, ld cst: la dispersion est dominée par les fluctuations spatiales de la vitesse et est amplifiée pour les fluides rhéofluidifiants ; aux vitesses élevées, ld augmente avec U (dispersion de Taylor) mais plus faiblement pour les fluides rhéofluidifiants. Pour une fracture avec deux parois autoaffines complémentaires décalées perpendiculairement à U, des chenaux macroscopiques s étendent sur toute la longueur de la fracture suivant U : l épaisseur globale du front augmente alors linéairement avec t et plus fortement dans le cas rhéofluidifiant (étalement advectif) mais la croissance locale est diffusive.PARIS-BIUSJ-Thèses (751052125) / SudocPARIS-BIUSJ-Physique recherche (751052113) / SudocSudocFranceF

Equivalent Hydraulic Conductivity, Connectivity and Percolation in 2D and 3D Random Binary Media

International audienceThe equivalent hydraulic conductivity () relates the spatial averages of flux and head gradient in a block of heterogeneous media. In this article, we study the influence of connectivity on of media samples composed of a high conductivity () and a low conductivity () facies. The facies is characterized by a proportion , and also by two connectivity parameters: a connectivity structure type (no, low, intermediate, high), and a correlation integral scale .The probability distribution of , and the critical value of at which percolation occurs (), are studied as a function of these connectivity parameters. The distribution of is Gaussian in all cases, so the results are presented in terms of the geometric mean () and the variance ().Both quantities show a data collapse if expressed as a function of (for the variance , notably, even if 2D and 3D data are plotted together). In 3D, when a connectivity structure exists, is always greater than when no structure exists, and increases (while decreases) as increases. The same is observed in 2D, except for the low connectivity structure type (i.e. when the facies is disconnected), that shows an unprecedented behaviour: is greater in the absence of structure, and decreases ( increases) as increases. Our results show that any influence of connectivity on is well accounted for simply by a shift in the percolation threshold , and then, suggest that is controlled mainly by the proximity to percolation